1. Field of the Invention
The invention is related generally to pistons for internal combustion engines, and more particularly to pistons having internal cooling chambers for cooling the pistons during operation.
2. Description of the Related Art
It is desirable for engine manufacturers to increase the temperature of the combustion of the air/fuel mixture in the combustion chamber of the cylinder in order to increase the fuel efficiency of the engine and decrease emissions. Therefore, there remains a significant and continuing need for improved pistons with cooling systems capable of allowing the piston to withstand increased temperatures.
However, with increased heat of combustion, there is a corresponding need to design pistons that can operate in such an environment. One approach has been to cool the upper region of the piston that is exposed to the heat of combustion by forming an open or a closed cooling chamber in the piston and directing a stream of cooling oil from below into the chamber to help extract some of the heat of combustion from the affected regions of the piston. Such a cooling approach, however, has its limits and may not be adequate or most efficient under all conditions. Another alternative approach has been to encapsulate a cooling medium, such as sodium, within a sealed chamber in the upper portion of the piston as the principle means to extract the heat of combustion from the piston. This too has its limits and cannot always adequately cool the piston with ever-increasing combustion temperatures.